All posts tagged Cyclone Gita

There has been widespread wind damage and flooding as Cyclone Gita passed over New Zealand, with the lower North Island and top half of the South Island worst affected. Some roads have been closed due to storm surge damage.

MetService meteorologist Karl Loots said former cyclone Gita passed over the South Island in the early hours of Wednesday morning, and by 5am was east of Banks Peninsula.

“Really the heavy rain now is focused from Canterbury down to Otago this morning, then that gradually eases. As well, we’ve still got gale force winds about Banks Peninsula and other exposed places in Canterbury, that’s all easing during this morning.”

Wellington Police are warning motorists that State Highway One is closed between Pukerua Bay and Paekakariki after it sustained weather damage overnight. The road was closed around 12:30am this morning as the high tide was washing across both lanes.

Fire and Emergency spokesman Joss Debreceny said firefighters had responded to more than 400 weather-related callouts between 2pm on Tuesday and 5am Wednesday.

Taranaki, Tasman and the West Coast were the busiest areas, with many callouts to roofs lifting, fallen trees and power lines, and flooding of houses and businesses.

Christchurch received about 50 per cent less rain on Tuesday night than forecast and high tide has passed without any major incidents.

There is still half a day of heavy rain and gale force winds possible for some areas, especially the east coast of the South Island as Gita heads southwards to the east of the country.

However it doesn’t look to have been as bad (so far) as some predictions.

– Gita has been downgraded to an ex-tropical cyclone. It’s caused mass disruption as it hits New Zealand.

– States of emergency have been declared in Taranaki, Nelson Tasman region, Selywn district, Grey district, Buller, Westland and Christchurch.

– Kaikōura is cut off after the Inland Rd was closed just after 8pm. State Highway 1 north of Kaikōura, from Mangamaunu to Clarence, and south between Peketa and Goose Bay, has been closed as of 8.30am.

– The Defence Force has been deployed in Takaka and has unimogs to help transport people, Nelson City Council communications manager Paul Shattock says.

– Air New Zealand cancelled all flights in and out of Wellington from 2.45pm until midnight Tuesday. It also cancelled services in and out of Hokitika, Nelson, New Plymouth, and Queenstown. A number of flights into Wellington airport are cancelled on Wednesday morning but operations look set to resume as normal from 7am.

– Its effects have been felt from the Taranaki district to Greymouth.

– There is a chance of coastal inundation from the Kāpiti Coast south and on the Kaikōura Coast.

Severe weather warnings have been issued as cyclone Gita approaches New Zealand today.

Tropical cyclone Gita zig zagged through the tropics last week, first tracking east, then swinging in a u-turn to head west,causing damage in Samoa, Tonga and Fiji as well as New Caledonia on it’s way. It then swung in an arc south west then southward, then south eastward towards the middle of New Zealand. While no longer tropical cyclone strength there are warnings it may cause major problems through heavy rain, strong winds and a storm surge (up to 7 metre swells).

Cyclone Gita is currently undergoing extra-tropical transition, and has been re-classified as ‘Former Cyclone Gita’. Although Gita is no longer a tropical cyclone, it’s still expected to significantly impact much of central New Zealand over the next 24 hours.

Heavy rain is already occurring from Taranaki southwards to the Sounds, and is expected to spread over Buller, Nelson and the remainder of Marlborough over the next few hours.

Strong winds are expected to develop early this afternoon into this evening for the entire country, with the potential for damaging wind gusts from Taranaki and Taihape south to Westland and Banks Peninsula, including Wellington.

Watches and warnings remain in effect for Strong Winds and Heavy Rain, available on metservice.com, along with your latest weather forecast.

So it looks like the top of the South Island is going to bear the brunt of Gita, in particular the Nelson and Buller areas, but with a much wider area affected.

So, how does this extra-tropical transition take place? When a well-developed tropical cyclone reaches its peak in the heart of the tropics, it has an eye. The eye is often fairly cloud-free, nearly circular, and surrounded by a ring of very active thunderstorms. In the early and middle parts of their lives, tropical cyclones stand up quite vertically in the atmosphere, like large columns.

Besides encountering cooler seas, tropical cyclones heading towards New Zealand eventually come under the influence of the westerlies. The westerlies of the mid-latitudes increase in strength with height, a phenomenon known as vertical wind shear. This shear almost literally chops off the upper part of the tropical cyclone and sweeps it away, not unlike a woodcutter chopping off the upper part of a coconut tree to leave a section just above the ground (except it’s a much more gradual and subtle process). Along with the lower sea temperatures of the mid-latitudes, this destroys the positive feedback processes within the cyclone.

What remains is the former tropical cyclone’s low-level circulation, which may get carried off in the westerlies or become the focus of further development if conditions are right. Either way, tropical cyclones approaching the New Zealand area undergo drastic changes of structure and appearance as they undergo this extra-tropical transition.

Metservice Severe Weather Warning:

Heavy Rain Warning

Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

Area: Nelson and BullerValid: 14 hours from 7:00am to 9:00pm TuesdayForecast: Expect 150 to 200mm of rain to accumulate in Nelson west of Motueka, and 90 to 150mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Marlborough including the Kaikoura CoastValid: 15 hours from 7:00am to 10:00pm TuesdayForecast: Expect 150 to 200mm of rain to accumulate about higher ground, and 90 to 140mm elsewhere. Peak intensities of 20 to 30mm/hr possible.

Area: Wellington and Kapiti CoastValid: 15 hours from 1:00am to 4:00pm TuesdayForecast: Expect 75 to 100mm of rain to accumulate during the period. Peak intensities 20 to 30mm per hour during the morning. Further lighter rain is expected from late Tuesday afternoon to midnight Tuesday.

Area: Canterbury Plains (excluding Christchurch)and High Country, the ranges of WestlandValid: 27 hours from 12:00pm Tuesday to 3:00pm WednesdayForecast: Expect 150 to 200mm of rain to accumulate during this period about Canterbury High Country, and 90 to 120mm elsewhere. Peak intensities of 20 to 30mm/hr possible about Canterbury High Country.

Strong Wind Warning

Strong wind gusts could damage trees, powerlines and unsecured structures. Driving may be hazardous, especially for high-sided vehicles and motorcycles.

Area: Taranaki, Taihape, WhanganuiValid: 10 hours from 3:00pm Tuesday to 1:00am WednesdayForecast: Severe gale north to northwest winds gusting 120 km/h in exposed parts of North Taranaki, but damaging gusts of 140 km/h in exposed parts of South Taranaki, Whanganui and Taihape.

Area: Westland and the Canterbury High Country near the AlpsValid: 13 hours from 12:00pm Tuesday to 1:00am WednesdayForecast: Severe gale southeast winds with damaging gusts of 150 km/h possible in exposed places.

Cyclone Gita is expected to approach New Zealand from the northwest early next week.There remains uncertainty with regards to the speed and track of Gita, but the passage of this system across New Zealand on Tuesday and Wednesday is likely to bring a period of highly impactful severe weather.

There is high confidence of severe gales and heavy rain spreading across central and northern New Zealand on Tuesday and Wednesday.

In addition, winds associated with Gita are likely to cause large waves to affect some coastal places, and the expected storm surge allow run-up of waves in some low-lying coastal places, particularly at high tide.

Tonga was hit by Cyclone Gita overnight. It is too soon to get an appreciation of the amount of damage but winds, heavy rain and a storm surge are likely to have been very damaging, but it is too soon to tell how devastating it has been.

The US Joint Typhoon Warning Centre earlier said it was hitting maximum sustained winds estimated at 233km/h.

Well-built framed homes can be damaged in category four winds, and most trees will be either snapped or uprooted and electricity and water outages could last anywhere from several days to weeks after the storm.

This story will unfold over the next day or two in Tonga, as Gita heads westwards towards (but possibly to the south of ) Fiji and then in the direction of New Caledonia. At some stage it is expected to turn south and may have some impact on New Zealand eventually.